PROJECT SUMMARY/ABSTRACT Herpes simplex virus type 2 (HSV-2) is one of the most common sexually transmitted pathogens and is responsible for 20 million new infections each year worldwide. HSV-2 genital infection is a leading cause of genital ulcer disease and increases the likelihood of acquiring other sexually transmitted diseases including HIV. HSV-2 infection may result in the development of self-limiting painful lesions in immune competent individuals but is a cause of severe morbidity in immune compromised populations and newborns exposed to virus in the birth canal. Asymptomatic shedding episodes occur frequently in HSV-2 infected individuals which makes transmission more likely. HSV-specific T cells and antibody secreting cells reside at epithelial sites of previous HSV infection and clear virus from the genital epithelium after reactivation. Boosting this local immune response by therapeutic immunization to rapidly control HSV-2 shedding is a logical vaccine strategy. Systemically-injected therapeutic HSV-2 vaccines have shown promise in reducing virus shedding and recurrent lesion rates in clinical trials but need to be improved. We propose that direct mucosal stimulation of genital resident, HSV-specific immune cells will result in improved vaccine efficacy over systemic boosting. Recently, prolonged delivery of recombinant HIV antigen and adjuvant to the vagina through an intravaginal ring (IVR) resulted in development of local antibody responses that exceeded those achieved by systemic immunization. As a proof-of-concept test of a therapeutic vaccination approach, we will use a novel pod-IVR delivery platform to deliver HSV immunogen/adjuvant to the vaginal mucosa, quantify the boosting effect on the genital-tract resident, vaccine antigen-specific B and T cell populations, and test the efficacy of the vaccine in protection against HSV-2 recurrent disease and virus shedding. Our long-term goal is to understand how to boost the function of genital tract-resident immune cells to enhance immune control of HSV-2 shedding. Our central hypothesis is that direct delivery of therapeutic vaccine antigen to the genital epithelium will boost genital tract-resident, HSV-specific T and B cells and increase control of HSV-2 shedding. Our objective in these studies is to test the concept that a therapeutic vaccine delivered by a novel pod-intravaginal ring will strongly boost genital-resident T and B cell responses and will prove effective in controlling virus shedding and recurrent disease. The Specific aims of this proposal are: Aim 1: Test direct delivery of recombinant HSV- 2 gD+gB/ CpG adjuvant to the female genital tract by pod-IVRs for therapeutic immunization against HSV-2; and Aim 2: Test protective efficacy of pod-IVR immunization of the female genital tract against HSV-2 recurrent disease and virus shedding. This work is significant because understanding how best to boost pre-existing genital-resident HSV-specific immune cells will be critical for improving the efficacy of therapeutic vaccines to reduce HSV-2 transmission.